Recent work indicates that indices of lexico-semantic connectivity in networks comprising individual children?s early vocabulary may relate to individual differences in vocabulary size. The underlying mechanisms for this relation are poorly understood, but word-learning biases that depend on relations between the semantic feature characteristics of words and an individual?s vocabulary are one possibility. This project seeks to clarify the relations between lexico-semantic development, word learning biases and word learning skill. Aim 1 seeks to explore individual differences in the relations between indices of lexico-semantic connectivity, attentional biases and novel word learning in children with a wide range of vocabulary sizes. We will assess attentional biases and word learning using established eye-tracking methods and vocabulary knowledge using an established parental checklist for a group of 90 children between the ages of 24 and 30 months. We ask if novel objects with greater semantic connectivity with the vocabulary of the individual child attract greater attention pre-labeling and/or make object-label associations easier to learn and interpret. Furthermore, we ask if these relations vary as a function of vocabulary size. Aim 2 seeks to explore individual differences in the relations between indices of semantic connectivity, attentional biases and known word processing. With the same participants and a word checklist tailored to the task, we ask if known objects with greater semantic connectivity attract greater attention pre-labeling and/or have object-label associations which are easier to interpret. Furthermore, we ask if these relations vary as a function of vocabulary size. This project aims to uncover whether and how individual differences in toddlers? word learning and processing skill relate to word- learning biases that depend on relations between the semantic feature characteristics of words and an individual?s vocabulary. If successful, this project will set the groundwork for more focused work in the future with at-risk children at the lower end of the vocabulary spectrum.